Antitumor photosensitizer HPPH belongs to the second generation photosensitizer, which is a kind of chlorin compound extracted, purified and semi-synthesized from green plants by the researchers of Roswell Park Tumor Institute in US. The structure formula is as follows:
HPPH has fairly well photodynamic activities, ideal action spectrum and good targeting as well as has high penetration rates to tumor tissues. In clinic, HPPH can be used in the treatment of lung cancer, esophageal carcinoma, head-face-neck cancer, bladder carcinoma, gastric cancer and many kinds of other solid tumors. Compared with the first generation photosensitizer, the phototoxicity of HPPH is obviously reduced and there is substantially no necessity for being protected from light. Further, the dosage is small and it is convenient to use, thus HPPH is a PDT photosensitizer for treating cancers with an extremely great market potential and it has become one hot topic in the research field of anticancer drugs recently. In foreign countries, the related Phase II clinical study has been conducted, but in China, the PDT market is nearly in blank and the present antitumor photosensitizer belongs to the first generation which has high toxicity and cost for treating. As a new generation photosensitizer, HPPH will surpass its competitive products and occupy beneficial position by virtue of its specific superiorities and relatively low price.
HPPH has fairly well anticancer effects, however, it has poor solubility in water and is unstable in water. It is reported that in the liquid injection used in the Phase II clinical study in foreign countries, during the process of preparing formulations of HPPH, excess feeds are required because of the solubility issue of the active component. Moreover, during the process of formulating a solution, the period of dissolving the active components is nearly 18 hours, and the storage condition for the obtained formulation is −20° C. as well as the term of validity is one year. Hence, such a liquid injection is not suitable for a large-scale manufacture and its application is extremely restricted. Further, it would bring about some improper influence to the safety and effectiveness of its clinical medication.